Hydrokinetic coupling appliance

ABSTRACT

A hydrokinetic appliance ( 10 ), in particular for a motor vehicle, comprising a housing ( 12 ) provided with an annular axial wall ( 13 ) and a front transverse wall ( 18 ), wherein the housing ( 12 ) is designed to be linked in rotation to an input shaft, which includes a turbine wheel ( 40 ) housed inside the housing ( 12 ) and integral with a hub ( 46 ), capable of being coupled in rotation with an output shaft, and wherein a locking clutch comprises a rear piston ( 30 ) axially mobile relative to the front transverse wall ( 18 ) of the housing ( 12 ). The rear piston ( 30 ) is coupled in rotation to the annular axial wall ( 13 ) of the housing ( 12 ) by an axially resilient device ( 64 ).

INTERNATIONAL PATENT APPLICATION NO. PCT/FR00/02156, PUBLICATION NO.WO01/07800A1

The present invention relates to hydrokinetic coupling apparatus for amotor vehicle.

The present invention relates more particularly to hydrokinetic couplingapparatus of the type which is described in the document FR-A-2 748 539.In that document the apparatus includes an input element in the form ofa casing having a generally transversely oriented wall and an outputelement comprising a turbine wheel assembled with a hub, which aretogether mounted inside the casing. A piston is located between thisassembly and the transverse wall. The piston is mounted for axialmovement with respect to the transverse wall and it is coupled inrotation to the latter.

The input element is arranged to be coupled in rotation through itstransverse wall to a driving shaft, while the output element is arrangedto be coupled in rotation to a driven shaft through its hub.

The piston has at its outer periphery a surface called the secondsurface, while the transverse wall has a first surface facing the secondsurface. The surfaces in this case are friction surfaces, with one ormore friction discs being interposed between the two surfaces.

By varying the pressure on either side of the piston, the latter isdisplaced axially in one direction or the other. The piston isaccordingly movable axially with respect to the hub.

In the said document, the friction disc is provided at its outerperiphery with lugs which extend outside the piston so as to mesh withan input member of a torsion damper, which includes an output memberhaving a damper plate coupled to the hub. Circumferentially actingelastic members act between the input and output members, which are soconfigured as to receive the elastic members, which lie radially outsidethe piston and the surfaces.

It can be desirable to increase the external diameter of the surfaces,which is not possible having regard to the presence of the elasticmembers.

Accordingly, an object of the present invention is to increase theoutside diameter of the surfaces, and to do so in an inexpensive way.

According to the invention, hydrokinetic coupling apparatus, especiallyfor a motor vehicle, of the type which comprises a casing having anannular axial wall and a transverse front wall, of the type in which thecasing is arranged to be coupled in rotation to a driving shaft, of thetype that includes a turbine wheel mounted inside the casing and fixedto a hub which is arranged to be coupled in rotation to a driven shaft,of the type in which the rear face of the transverse front wall of thecasing includes a first surface, of the type in which a lock-up clutchis interposed operatively between the turbine wheel and the transversefront wall so as to couple them together releasably, and of the type inwhich the lock-up clutch comprises at the rear a piston which is movableaxially with respect to the transverse front wall of the casing, andwhich carries on its front face a second surface facing the firstsurface, is characterised in that the piston is coupled in rotation tothe annular axial wall of the casing through an axially elastic device.

Thanks to the invention it is possible to increase the outside diameterof the surfaces, because there is no longer any restriction due to thepresence at the outer periphery of the transverse wall of the casing ofa damping device or a device for coupling the piston to the casing.

According to further features of the invention:

the second surface is situated in the vicinity of the outer periphery ofthe piston;

the axially elastic device comprises at least one support member coupledin rotation and axially to the axial annular wall of the casing andcomprising a transverse plate element, and comprises at least oneelastic member which is interposed axially between the piston and thetransverse plate portion of the support member, and the piston includesmeans for coupling it in rotation with the support member;

the mean radius of intervention of the elastic member is smaller thanthe external radius of the second surface;

the axially elastic device comprises a plurality of support membersspaced apart circumferentially, in particular at regular intervals;

the axially elastic device comprises a single support member, thetransverse plate portion of which constitutes an annular ring;

the piston includes at its outer periphery an axial skirt which extendstowards the rear and includes notches, and the transverse plate portionor portions of the support member or of the respective support member,constitute annular ring sectors, such that the annular ring sectors arereceived in the notches of the axial skirt of the piston, whereby toenable the support members to come into abutment against the edges ofthe notches in the piston;

the transverse plate portion of the support member has notches, and thepiston includes pads on its rear face facing the said notches, wherebythe pads of the piston are received in the notches of the transverseplate portion so as to couple the piston in rotation with the supportmember;

the coupling in rotation between the piston and the support member ormembers includes a circumferential clearance;

the axially elastic device comprises axially elastic tongues, theopposed ends of which are secured respectively on the piston and on thetransverse plate portion of the support member or members;

the tongues exert a preloading force on the piston in the direction oflocking of the clutch;

the magnitude of the preloading force is adjusted according to the axialpositioning of the transverse plate portion;

the tongues tend to retain the piston in the unlocked position of theclutch;

the tongues are spaced apart circumferentially at regular intervals;

the tongues are oriented tangentially;

each tongue includes a first point for fastening on the rear face of thepiston;

the first fastening point is defined on a convex boss on the rear faceof the piston;

the tongues are formed integrally with the transverse plate portion orportions of the or the respective support member;

each tongue has a second point for fastening on the front face of thetransverse plate portion or portions of the or the respective supportmember;

the second fastening point of the tongue is in facing relationship witha concave boss on the rear face of the piston;

the transverse plate portion of the support member is formed withcut-outs in facing relationship with a first fastening point of eachtongue, the second fastening point of which is situated in the vicinityof the circumferential terminal edge of the cut-out;

the axially elastic device comprises at least one compression spring inaxial engagement, firstly on the rear face of the piston and secondly onthe front face of the transverse plate portion or portions of the or therespective support member, whereby the spring exerts a preloading forceon the piston in the direction of locking of the clutch;

the axially elastic device comprises a single annular spring of thehelical type or of the conical type or of the corrugated type;

the axially elastic device comprises a plurality of compression springswhich are spaced apart circumferentially at regular intervals;

each compression spring is of the helical type, and at least one end ofeach spring is hooked on a retaining pad formed in projectingrelationship on the front face of the transverse plate portion orportions of the or the respective support member and/or on the rear faceof the piston;

each compression spring is a spring sector of the conical ring type orcorrugated type;

the transverse plate portion or portions of the or the respectivesupport member include at their inner periphery an axial skirt whichextends forward so as to retain the springs radially inwards;

the transverse plate portion or portions of the or the respectivesupport member includes pairs of circumferentially opposed abutments,which extend axially forwards to retain the spring sectorscircumferentially;

each spring sector of the corrugated type is fixed through itscircumferential ends on the transverse plate member or members of the orthe respective support members;

the axial annular wall of the casing includes transverse lugs whichextend towards the axis and each of which has a notch, and the supportmember includes on its outer periphery transverse lugs, each of whichhas on its rear face a projecting boss facing a recess, whereby thesupport member is coupled in rotation with the axial wall of the casingby a bayonet type coupling;

the piston includes, in facing relationship with its rear face, at leastone transverse intermediate plate which is fixed through its outerperiphery on a peripheral annular skirt of the piston, whereby theelastic member is operatively interposed between each transverseintermediate plate and each support member;

the casing comprises a front shell and a rear shell, each of whichincludes an axial skirt, the two axial skirts defining the axial annularwall of the casing;

the transverse plate portion of each support member is fixed directly onthe free rear end of the axial skirt of the front shell, or on the freefront end of the axial skirt of the rear shell;

each support member comprises an annular axial crown or annular axialcrown sectors, which are oriented towards the rear from the outerperiphery of the transverse plate portion, for coupling the supportmember to the axial annular wall of the casing;

the crown or the crown sector of each support member is fixed on theaxial skirt of the front shell or on the axial skirt of the rear shell;

the crown or the crown sector of each support member is fixed betweenthe axial skirt of the front shell and the axial skirt of the rearshell;

a double-sided annular friction disc is arranged to be gripped betweenthe first and second surfaces, and a torsion damper is interposedoperatively between the annular friction disc and the hub of theturbine.

Further features and advantages of the invention will appear on areading of the following detailed description, for an understanding ofwhich, reference will be made to the attached drawings, in which:

FIG. 1 is a half view, partly in axial cross section, showing ahydrokinetic coupling apparatus made in accordance with the invention ina first embodiment, in which the axially elastic device comprisesaxially elastic tongues, and in which the support member is secured bywelding on the internal wall of the front axial skirt;

FIG. 2 is a view in axial cross section, on a larger scale, of theaxially resilient device of the hydrokinetic coupling apparatus in FIG.1;

FIG. 3 is a front view, taken in cross section on the line 3-3 in FIG.2, of the axially resilient device of the hydrokinetic couplingapparatus of FIG. 1;

FIG. 4 is a view similar to that in FIG. 2, showing a second embodimentof the invention in which the support member is fitted and weldedbetween the front axial skirt and the rear axial skirt of the casing;

FIGS. 5 and 6 are views similar to those in FIGS. 2 and 3, showing athird embodiment of the invention in which the support members are fixedon the free front end of the rear axial skirt of the casing;

FIGS. 7 and 8 are views similar to those in FIGS. 2 and 3, but show afourth embodiment of the invention in which the support members arefixed on the free rear end of the front axial skirt of the casing;

FIGS. 9 and 10 are views similar to those in FIGS. 2 and 3, but show afifth embodiment of the invention in which the axially elastic tonguesare integral with the support member;

FIGS. 11 and 12 are views similar to those in FIGS. 2 and 3, but show asixth embodiment of the invention in which the piston includes arearwardly oriented axial skirt which is in cooperation with the supportmembers;

FIG. 13 is an exploded perspective view showing the main components ofthe sixth embodiment of the invention;

FIGS. 14 and 15 are views similar to those in FIGS. 2 and 3, but show aseventh embodiment of the invention in which the piston includestransverse intermediate plates for fastening the elastic tongues;

FIGS. 16 and 17 are views similar to those in FIGS. 2 and 3, but show aneighth embodiment of the invention in which the elastic device consistsof compression spring sectors of the conical ring type;

FIGS. 18 and 19 are views similar to those in FIGS. 2 and 3, but show aninth embodiment of the invention in which the spring sectors are of thecorrugated type;

FIG. 20 is a top plan view in the direction of the arrow F20 in FIG. 19,partly cut away, and is a scrap view showing the ninth embodiment of theinvention;

FIGS. 21 and 22 are views similar to those in FIGS. 2 and 3, but show atenth embodiment of the invention in which the spring sectors arereplaced by compression springs of the helical type;

FIGS. 23 and 24 are views similar to those in FIGS. 2 and 3, but show aneleventh embodiment of the invention in which the elastic deviceconsists of a single compression spring of large diameter and of thehelical type;

FIGS. 25 and 26 are views similar to those in FIGS. 2 and 3, but show atwelfth embodiment of the invention in which the axially elastic deviceis mounted in the casing by a bayonet type connection;

FIG. 27 is an exploded perspective view showing the main components ofthe twelfth embodiment of the invention.

In the following description, those elements which are identical orsimilar to each other will be given identical references. A front torear orientation will be employed which corresponds to the orientationfrom left to right in the views seen in axial cross section and theperspective views.

In addition, for each embodiment only those elements will be describedwhich are different from one embodiment to another.

FIG. 1 shows a general view of a hydrokinetic coupling apparatus 10. Theapparatus 10 comprises a casing 12 which consists in particular of afront shell 14 and a rear shell 16.

The front shell 14 has a transverse front wall 18 and an annular frontaxial skirt 20 which extends towards the rear.

The rear shell 16 defines a semi-toroidal annular rear envelope 22, andincludes an annular rear axial skirt 24 which extends forward and whichis received axially within the front axial skirt 20.

A transversely oriented first annular surface 26 is formed at the outerperiphery of the inner face of the front transverse wall 18.

A transversely oriented second annular surface 28 is formed at the outerperiphery of the front face of a piston 30 at the rear.

The surfaces 26 and 28 are integral, in this example, with thetransverse front wall 18 and the piston 30 respectively. In anotherversion, at least one of the surfaces 26 and 30 may be part of anadditional component which is for example fixed by welding on theelement concerned.

The piston 30 is mounted so that it can be displaced axially withrespect to the front transverse wall 18, which has a central externalcentring nose 32 projecting axially and of generally tubular form.

The axial front skirt 20 is centred in the region of its free rear endon the free front end of the rear axial skirt 24. The front axial skirt20 is therefore in intimate contact through its inner face 21 with theouter peripheral face 25 of the rear axial skirt 24, and is secured, inthis case by means of a weld 23, on the rear axial skirt 24. The twoaxial skirts 20 and 24 thus constitute an axial annular wall 13 of thecasing 12.

The vanes 34 of an impulse wheel 36 are secured internally on thesemi-toroidal envelope 22. The vanes 34 face towards the vanes 38 of aturbine wheel 40, and the piston 30 is disposed axially between theturbine wheel 40 and the front transverse wall 18.

The said turbine wheel 40 has an internal annular ring 42, which may beof divided form, and through which it is secured, in this example bymeans of rivets 44, or in another version by welding, on the outerperiphery of a hub 46 which extends axially forward and which isgenerally L-shaped in axial cross section.

It is on the transversely oriented portion 48 of the hub 46, in the formof a radial plate, that the ring 42 is fixed, while the axially orientedtubular portion 50 of the hub 46 has internal splines which couple thehub 46, and therefore the turbine wheel 40, in rotation with a drivenshaft (not shown).

The driven shaft is, in a known way, provided with a central duct forfeeding a hydraulic control chamber 52 which is bounded axially by thepiston 30 and the transverse front wall 18, and radially, andinternally, by the axial portion 50 of the hub 46.

To this end, at least one passage 54 exists between the free end of theaxial portion 50 and the front transverse wall 18, for passage of thecontrol fluid, oil in this case, that comes from the duct in the drivenshaft.

The axial portion 50 is generally tubular in form and it has externalsplines 56 in the region of its free front end.

The axial portion 50 has, between the radial plate 48 and splines 56, anexternal smooth surface 58, the diameter of which is slightly greaterthan that of the splines 56 so that the axial portion 50 is of steppeddiameter.

A ring seal 60 is fitted in a groove formed in the surface 58. This seal60 co-operates with an axially oriented sleeve element 62 which is partof the piston 30 at its inner periphery. In this way, sealing isobtained in this region.

In accordance with the features of the invention, the hydrokineticcoupling apparatus 10 includes an axially elastic device 64 whichcouples the piston 30 in rotation to the annular axial wall 13 of thecasing 12.

FIG. 2 shows on a larger scale the axially elastic device 64 in a firstembodiment.

In the first embodiment of the invention, the axially elastic device 64comprises a support member 66 which consists of a transverse annularplate portion 68 at the outer periphery of which there is a rearwardlyoriented annular axial crown portion 70.

The support member 66 is fixed on the annular axial wall 13 of thecasing 12, in this example by welding the annular axial crown portion 70on the internal face 21 of the axial front skirt 20, to form a weld seam19.

Welding of the annular axial crown portion 70 is for example of thelaser type or the electrical type or the resistance welding type or thefriction welding type.

In a modified embodiment (not shown) of the invention, the supportmember 66 is force fitted into the casing 12, or it is seamed in thecasing 12.

The transverse plate portion 68 has cut-outs 72 at its inner radialperiphery, one of which can be seen face on in FIG. 3.

The axially elastic device 64 also includes axially elastic tongues 74,the opposed tangential ends of which are fixed through a first fasteningpoint 76 on the rear transverse face 78 of the piston 30, and, through asecond fastening point 80, on the front transverse face 82 of thetransverse plate portion 68.

The first fastening point 76 lies facing a cut-out 72 of the transverseplate portion 68, while the second fastening point 80 is located in thevicinity of a circumferential terminal edge 73 of the cut-out 72.

Fastening of the tongues 74 is achieved here by means of rivets, but itcan be obtained in other known ways.

It is noted that the rear face 78 of the piston 30 includes, in theregion of the first fastening point 76, a convex boss 84 which projectsin relief axially towards the rear, and, facing the second fasteningpoint 80, a concave boss 86, the object being to limit the axial size ofthe device 64.

The number of tongues 74 depends on the application, these being spacedapart circumferentially at regular intervals in several sets of tongues74, in which each set comprises at least one tongue 74 in this example.The device 64 may for example have three sets of tongues 74.

The tongues 74, which in this case are oriented generally tangentially,may be oriented transversely, being for example triangular orrectangular.

In all cases the piston 30, radially inside its surface 28, matches theform of the turbine wheel 40 and hub 46 so as to reduce the size of thehydrokinetic coupling apparatus 10, which consists of the turbine wheel40, impulse wheel 36, piston 30, hub 46 and a torsion damper 90, whichin this example is of a standard type.

The hydrokinetic coupling apparatus 10 has an axis X-X′ of axial androtational symmetry. In this example the apparatus 10 also includes areaction wheel 88 so as to constitute a torque converter in the knownway.

The casing 12 is sealed and filled with oil.

The torsion damper 90 is interposed between the piston 30 and the fronttransverse wall 18, so as to filter out vibrations, the damper 90 actingdisengageably between the piston 30 and hub 46.

More precisely, the damper 90 in this case is of the two-stage type, andit includes an annular friction disc 92 which is arranged to be grippedaxially between the surfaces 26, 28.

The friction disc 92 is coupled, through a first elastic damping stagewhich in this example consists of circumferentially oriented helicalcompression springs 93, to a central damper plate 94 which is splinedinternally for mounting on the external splines 56 of the hub 46. Thedamper plate 94 is in mesh with the hub 46, in this case with acircumferential clearance.

The friction disc 92 is also coupled, through a second elastic dampingstage which in this example consists of circumferentially orientedhelical compression springs 95, to a lateral damper plate 97 which issplined internally for fitting without any circumferential clearance onthe splines 56 of the hub 46.

Two-stage torsion dampers are well known in the state of the art, andthe two damping stages will not be described in any greater detail here.

As will have been understood and as is well known, by varying thepressure on either side of the piston 30, for example by varying thepressure in the hydraulic control chamber 52 through the feed duct inthe driven shaft and through the passage 54, the piston 30 is displacedforward or backward so that, in one case, it grips the friction disc 92between the surfaces 26, 28, and in the other case it releases thefriction disc 92.

When the friction disc 92 is gripped, the lock-up clutch which includesthe surfaces 26, 28 and the torsion damper 90 is said to be engaged orbridged, so that the rotary driving motion is transmitted directly fromthe driving shaft (not shown), which is for example the crankshaft of amotor vehicle in the case of application to a motor vehicle, to thedriven shaft, through the lock-up clutch without any relative slidingmovement between the turbine wheel 40 and impulse wheel 36. Inparticular, this reduces the fuel consumption of the vehicle.

When the friction disc 92 is released, the lock-up clutch is said to bedisengaged or unbridged, so that the rotary driving movement istransmitted from the driving shaft to the driven shaft through thetorque converter by virtue of the flow of oil between the vanes 34, 38of the impulse wheel 36 and turbine wheel 40. This is, in particular,what happens on starting of the motor vehicle.

The tongues 74 enable the piston 30 to move axially with respect to thefront transverse wall 18 when the lock-up clutch is shifting from oneposition to the other.

Preferably, but without limitation of the invention, the tongues 74 areso mounted that they exert an axial preloading force on the piston 30 inthe direction of bridging of the lock-up clutch. In consequence, inorder to unbridge the lock-up clutch, the pressure in the hydrauliccontrol chamber 52 is increased.

It will be noted that the magnitude of the preloading force exerted onthe piston 30 can be adjusted as a function of the axial positioning ofthe transverse plate portion 68. The further forward the transverseplate portion 68 is located, the greater is the preloading force.

In a modified embodiment of the invention, the tongues 74 are so mountedthat they tend to retain the piston 30 in its unbridged position.

The tongues 74 can of course be fixed by any known means on the piston30 and support member 66. For example, they can be secured by means ofrivets, the bodies of which are extruded on the piston 30 or supportmember 66, or by welding, or by screw fastening.

In this example the friction disc 92 carries front and rear frictionliners 96, secured on each of its opposed transverse faces. In anotherversion, the liners 96 are fixed to the surfaces 26, 28, which aretherefore fastening surfaces. In a further version, the friction disc 92is embedded at its outer periphery within a friction liner. In yetanother version, the friction disc 92 is in direct frictional contactagainst the surfaces 26, 28.

Preferably, the liner or liners 96 are provided with grooves extendingfrom their inner periphery to their outer periphery to give goodcooling, the grooves being in contact with the surfaces 26, 28 or withthe friction disc 92.

The hydrokinetic coupling apparatus 10 made in accordance with theinvention enables the torque transmission capacity of the driven shaftto be increased because of the increase in the mean radius of thesurfaces 26, 28, which are no longer radially limited in size by thepresence of a device on the outer periphery of the transverse front wall18 of the front shell 14.

In addition, the invention reduces the number of components required, ascompared with the state of the art, thus reducing the cost of theapparatus 10.

The use of an axially elastic device 64 such as that of the invention,which exerts a preloading force on the piston 30 in the direction ofbridging of the lock-up clutch, enables a gripping force to be exertedon the friction disc 92 without application of any pressure on thepiston 30.

A friction means 41 acts between a front transverse surface 43 formed onthe radial plate portion 48 of the hub 46 and the piston 30, which iscoupled releasably to the front transverse wall 18 through the secondsurface 28 which lies facing the first surface 26 as described above.

The friction means 41 prevents any direct contact taking place betweenthe piston 30 and the transverse surface 43 of the hub 46, and limitsaxial displacement of the piston 30 towards the rear, thereby preventingthe latter from coming into contact with the turbine wheel 40.

The friction means 41 comprises at least one friction element,preferably having a low coefficient of friction. This friction elementis preferably of synthetic material such as plastics, which can withadvantage be reinforced by fibres and/or balls such as glass fibresand/or balls.

It will be noted in FIG. 1 that the piston 30 is adjacent to theassembly of the turbine wheel 40 and hub 46, and is so configured as tocarry the friction means 41, while the hub 46 has an axially orientedannular portion directed towards the front transverse wall 18 andsurrounded by the piston 30, which is mounted for axial movement withrespect to the said portion.

Thanks to this arrangement, the radial plate portion 48 of the hub 46does not need to be given any additional machining operation, becausethe friction means 41 is carried by the piston 30.

Another result is that the mechanical strength of the plate portion 48is preserved, and in addition the solution is simple and inexpensivebecause the piston 30, which is preferably made of metal, is a componentwhich it is easy to configure.

All of this combines well with the damper 90, because the piston 30 islocated axially between the damper 90 and the assembly of the turbinewheel 40 and hub 46, coming as close as possible to the said assembly,and in particular to the plate portion 48.

In addition, the piston 30 is coupled in rotation to the axial wall ofthe casing 12, which enables a radial clearance to be provided betweenthe sleeve element 62 and the surface 58 so that there is no danger ofthe piston 30 jamming.

The piston 30 is in cooperation, through its sleeve element 62, onlywith the seal 60 which is mounted on the hub 46, so that the frictionmeans 41 have a good surface of contact with the plate portion 48, sincethe tongues 74 and seal 60 enable the piston 30 to be displaced, inparticular circumferentially, so that the surface contact between thefriction means 41 and plate portion 48 is always maximised.

In this example, one of the means 41 in frictional engagement with thepiston 30 has at least one projecting element which is engaged in acomplementary hole 45 in the rear face 78 of the piston. This matingcooperation is simple and inexpensive to achieve, and enables thefriction means 41 to be well centred while providing a rotary coupling.

The hole 45 is preferably blind, so that sealing of the chamber 52 ispreserved. The blind hole 42 is preferably press-formed or extruded.

The friction means 41 consists of a ring which is arranged to makecontact with a transverse surface 43 of the hub 46 formed on the plateportion 48 radially inside the fastening rivets 44.

The said transverse surface 43 faces forward.

The ring 41 has a plurality of bosses 47, each of which is engaged, inthis example with axial and radial clearance, in a blind hole 45 formedlocally by forward extrusion of the metal of the piston 30.

The bosses 47 and holes 45 are cylindrical, being of circular crosssection here, but in modified versions they are of square cross sectionor of any other form.

The contact surface 43 between the plate portion 48 and ring 41 ismaximised because of the mounting of the bosses 47 in the holes 45 withaxial and radial clearance.

FIG. 4 shows a second embodiment of the axially elastic device similarto the foregoing one, but in which the axial annular crown 70 isinserted axially and radially between the internal face 21 of the frontaxial skirt 20 and the outer face 25 of the rear axial skirt 24, so thatthese three elements are secured together, in this example by welding ina single weld seam 23.

FIGS. 5 and 6 show a third embodiment of the axially elastic devicewhich comprises a plurality of support members 66 defining lugs.

These support lugs 66 are preferably spaced apart circumferentially atregular intervals, and there are for example three of them.

It will be noted that in this embodiment, the support lugs 66 do notinclude the axial annular crown element 70 as in the previous versions.

Each support lug 66 comprises a sector 100 of the annular transverseplate portion 68. The sector 100 of the annular transverse plate portion68 has at its outer periphery crenellations 102 which fit betweencomplementary lugs 104 extending axially forward from the front free endof the rear axial skirt 24 of the rear shell 16.

Fastening of the crenellations 102 on the lugs 104 may be obtained forexample by seaming or welding.

Each transverse plate sector 100 includes on its front transverse face82 a second fastening point 80 for an axially elastic tongue 74.Assembly of the tongue 74 to the second fastening point 80 is of thesame type as that in the first embodiment.

The fourth embodiment of the axially elastic device which is shown inFIGS. 7 and 8 is similar to the second embodiment.

A first difference is that the rear axial skirt 24 is centred in theregion of its free end around the free rear end of the front axial skirt20, and is secured on the front axial skirt 20, by welding in thisexample.

A second difference is that the lugs 104 are part of the free rear endof the front axial skirt 20. Thus, the support lugs 66, which areidentical to those in the second embodiment, are engaged through theircrenellations 102 between the lugs 104 of the front axial skirt 20.

FIGS. 9 and 10 show a fifth embodiment which is similar to the fourthembodiment, but in which each axially elastic tongue 74 is integral withthe transverse plate sector 100 of a support lug 66.

Thus the transverse plate sector 100 no longer includes the secondfastening point 80. The radially inner periphery of the transverse platesector 100 is extended substantially circumferentially by a tongue 74,which is extended up to a first fastening point 76, which is stillsituated on a convex boss 84 on the rear face 78 of the piston 30.

It will be noted that, preferably, the transverse plate sector 100 liesin the same transverse plane as the tongue 74.

FIGS. 11, 12 and 13 show a sixth embodiment of the invention which isclose to the third embodiment.

The sixth embodiment differs, in the first place, in that each supportlug 66 comprises an annular crown sector 106 similar to the crown 70,which is secured, by welding at 19 in this example, on the internal face21 of the front axial skirt 20.

In the second place this embodiment is different in that the piston 30includes at its outer periphery an axial skirt 108 which extends towardsthe rear.

The free rear end 109 of the axial skirt 108 of the piston has notches110 facing each support lug 66.

The circumferential terminal edges 112 of each notch 110 are arranged tocome into abutment against the radial edges 114 of each transverse platesector 100.

It will be noted that the fitting of the support lugs 66 in the notches110 is obtained with a circumferential clearance, in particular to avoidany interference with the axial displacement of the piston 30.

The circumferential terminal edges 112 of the notches 110 act as acircumferential abutment for the support lugs 66, which prevents anybuckling of the axially elastic tongues 74 when a high torque is beingtransmitted by the assembly of the casing 12 and piston 30 that givesrise to a longitudinal compression force on the tongues 74.

In FIG. 13, the convex bosses and concave bosses 86 will be noted on therear face of the piston 30.

FIGS. 14 and 15 show a seventh embodiment in which the piston 30carries, in facing relationship with its rear transverse face 78,transverse intermediate plates 116, the piston 30 also having an axialskirt 108 similar to that in the preceding embodiment.

Each transverse intermediate plate 116 includes an ear 117 which carriesthe first fastening point 76 for an axially elastic tongue 74.

Each intermediate transverse plate 116 has, at its outer periphery,transverse fastening lugs 120, each of which is engaged in acomplementary slot 122 formed in the free rear terminal edge of theaxial skirt 108 of the piston 30.

A support member 66 in the form of a lug is fixed on the axial frontskirt 20 in facing relationship with each intermediate transverse plate116, the rear axial skirt 24 being centred around the front axial skirt20 as in the fourth embodiment.

This support lug 66 comprises a transverse plate portion 126, at theouter periphery of which there is an annular crown sector 128 which iscentred internally in the front axial skirt 20. The transverse plateportion 126 has an ear 130 which carries the first fastening point 80for the axially elastic tongue 74.

The free rear end of the annular crown sector 128 includes transversefastening lugs 132, each of which is engaged, radially on the outside,in a complementary notch 134 formed in the free end of the front axialskirt 20.

Two transverse fastening lugs 120 and 132 are provided for eachtransverse intermediate plate, and for each support lug 66. This numberdoes of course depend on the application.

By upsetting the side edges of the notches 122, 134 by cold or hotworking, for example with electric heating, the metal of the axial skirt108 of the piston 30 and that of the front axial skirt 20 of the frontshell 14 respectively is caused to flow so as to enable the transversefastening lugs 120, 132 to be axially immobilised, respectively, betweenthe base of the notches 122, 134, and it also enables the material toreflow during plastic deformation of the side edges of the notches 122,134. Thus the transverse intermediate plate 116 and the support lug 66are seamed, in this example, respectively on the axial skirt 108 of thepiston 30 and on the front axial skirt 20 of the front shell 14.

In another version, the front axial skirt 20 of the front shell 14 canpartly surround the rear axial skirt 24 of the rear shell 16, so thatthe notches 134 can be formed in the axial rear skirt 24.

In a further version, the transverse fastening lugs 120, 132 arefastened by welding or adhesive bonding, respectively on the axial skirt108 of the piston 30 and on either the front axial skirt 20 or the rearaxial skirt 24 of the casing 12.

In yet another version, the annular crown sector 128 of the support lug66 is secured by welding, for example by transparency welding of thelaser type, on the front axial skirt 20 of the front shell 14.

In yet a further version, the transverse intermediate plate 116 can bewelded directly on the rear face 78 of the piston 30. The transverseintermediate plate 116 accordingly has a first portion for fastening theend concerned of a set of tongues 74, and a second portion, offsetaxially, for fastening of the transverse intermediate plate 116 bywelding.

In yet a further version, the piston 30 can also have at its outerperiphery a transverse flange, which may be divided into lugs and whichis directed towards the axis X-X′ so that it then replaces thetransverse intermediate plate 116 in that it carries the first fasteningpoint 76 for the tongue 74.

FIGS. 16 and 17 represent an eighth embodiment of the axially elasticdevice 64, in which the axially elastic tongues are eliminated.

In this embodiment, the elastic member consists of a plurality ofcircumferential sectors or portions 136 of a compression spring of theconical ring type, also referred to as a Belleville ring.

In this embodiment, the piston 30 comprises an axial skirt 108 which isoriented towards the rear and which is of a similar form to that of thepiston 30 in the sixth embodiment.

The support members 66 include transverse annular plate sectors 138which are provided at their outer periphery with an annular rear axialcrown sector 139, and at their inner periphery with an annular frontaxial crown sector 142.

Each support member 66 is fixed to the internal wall 21 of the axialfront skirt 20 through the outer wall of its annular rear axial crownsector 139, in this case by welding at 19.

As in the sixth embodiment, the axial skirt 108 of the piston 30 hasnotches 110 in facing relationship with each support member 66, so thatthe piston 30 is coupled in rotation with the support members 66 with acircumferential clearance. The circumferential terminal edges 112 of thenotches 110 are therefore able to come into abutment against thecircumferential terminal edges 114 of each transverse plate sector 138.

The piston 30 is driven by cooperation of the notches 110 with thesupport member 66.

Each spring sector 136 bears through its circular rear axial internalterminal edge 135 on the transverse front face of the transverse platesector 138, and through its circular front axial outer terminal edge 137on the rear transverse face 78 of the piston 30, preferably facing thesurfaces 26, 28.

Each spring sector 136 is retained radially at its inner periphery bythe annular front axial crown sector 142 of the support member 66. It isalso retained circumferentially by a pair of circumferential abutments140, which in this example consist of flanges extending axially forwardfrom the circumferential terminal edges 114 of each transverse platesector 138.

It will be noted that, besides exerting an axial preloading force on thepiston 30 in the direct of bridging of the clutch, the compressionspring 136 enables noise in the driving of the piston 30 by the supportmembers 66, due to the circumferential clearance, to be reduced becauseof the friction that exists between the piston 30 and the compressionspring 136.

FIGS. 18, 19 and 20 represent a ninth embodiment of the axially elasticdevice which is similar to the preceding embodiment, and in which thespring sectors of the conical ring type are replaced by compressionspring sectors 142 of the corrugated type.

In this embodiment, the support members 66 are similar to those in thepreceding embodiment, but they do not have any flanges at theircircumferential terminal edges, nor do they have any radially internalfront annular axial crown.

The piston 30 is identical to that in the preceding embodiment.

Each spring sector or portion 142 of the corrugated type includes at itsends retaining lugs 144 which are bent around circumferential terminaledges of each transverse plate sector 138, so that the spring sectors142 are coupled both in rotation and axially with the transverse platesectors 138. The elastic gripping of the lugs 144 around the transverseplate 138 also retains the springs 142 radially.

FIGS. 21 and 22 show a tenth embodiment similar to the precedingembodiment, in which each spring sector of the corrugated type has beenreplaced by a compression spring of the helical type 146.

The piston 30 and the support members 66 are similar to those in thepreceding embodiment.

However, each transverse plate sector 138 includes a retaining pad 148which is formed on its front face from which it projects, substantiallyin its centre and in this example by stamping out in the press, wherebyto immobilise the helical spring 146 transversely. Each helical spring146 may with advantage be hooked axially on its pad 148, with a view tomaking it easier to fit.

FIGS. 23 and 24 show an eleventh embodiment which is substantiallysimilar to the eighth embodiment, and in which the spring sectors of theconical ring type have been replaced by a single compression spring 150of the helical type.

It will be noted that the transverse plate portion 138 of, the supportmember 66 differs from the transverse plate portion in the eighthembodiment in that it includes on its front face a centring channel 152,which receives the rear axial end of the helical spring 150.

It will be noted that the annular rear axial crown sector 139, thetransverse plate portion 138, the centring channel 152 and the annularfront axial crown sector 142 give the support member 66 an S-shapedprofile.

The annular front axial crown sector 142 retains the helical spring 150radially towards the axis.

By way of modification, the single spring 150 of large diameter may be aBelleville ring or a corrugated ring in one piece.

FIGS. 25, 26 and 27 show a twelfth embodiment in which the mounting bywhich the support member 66 is supported in the casing 12 is of thebayonet type.

In this embodiment, the annular front axial skirt 20 of the front shell14 includes at its free rear end transverse lugs 154, each of whichextends radially towards the axis.

These transverse lugs 154 are spaced apart circumferentially at regularintervals and in pairs, of which there are three in this example, insuch a way that two transverse lugs 154 define a recess 156 betweenthem.

The support member 66 comprises a transverse annular plate portion 158which is axially stepped.

The transverse annular plate portion 158 has at its outer peripherytransverse lugs 160 of which there are three in this example, and whichare spaced apart circumferentially at regular intervals.

Each transverse lug 160 includes, projecting from its rear face 162, aboss 164 which is arranged to fit in a recess 156. The transverse lugs160 also include at their outer periphery an axial skirt 166 orientedtowards the rear.

The transverse annular plate portion 158 also includes, projecting onits front face, guide lugs 168 which in this example are formed bystamping out in the press, and, on its inner periphery, retainingnotches 170.

The piston 30 includes, projecting on its rear face 78 and facing eachretaining notch 170, a retaining pad 172.

A compression spring 150, which in this example is of the helical typeand which is of large diameter, is interposed between the piston 30 andthe transverse annular plate portion 158. This spring 150 is in axialabutment through its rear end on the front face of the transverseannular plate portion 158, and is in axial abutment through its frontend on the rear face 78 of the piston 30.

In this example, the spring 150 lies facing the surfaces 26 and 28, andit is retained radially on the side of the support member 66 by theguide lugs 168 and by an appropriate stepped configuration of thetransverse annular plate portion 158.

The piston 30, spring 150 and support member 66 are held in the casing12 by a coupling of the bayonet type. In consequence it is sufficient tocompress the spring 150 between the piston 30 and the transverse annularplate portion 158 by displacing the transverse annular plate portion 158axially forwards. Then, when the transverse lugs 154 of the front axialskirt 20 have been passed axially, a rotational movement is applied tothe transverse annular plate portion 158 so that each boss 164 of atransverse lug 160 of the transverse annular plate portion 150 comesinto engagement in a recess or notch 156 in the axial front skirt 20.

In accordance with the properties of the bayonet type fitting, thereturn force of the spring 150 maintains the transverse annular plateportion 158 in the casing 12 and the piston 30 against the transversefront wall 18 of the front shell 14, preventing any danger of accidentaldisconnection.

Various embodiments of the invention are described above. Thisdescription is of course not restrictive of the invention, and otherembodiments, not described here, may be envisaged. It is in particularpossible to combine some of these embodiments together.

What is claimed is:
 1. Hydrokinetic coupling apparatus (10), for a motorvehicle, which comprises a casing (12) having an annular axial wall (13)and a transverse front wall (18), in which the casing (12) is arrangedto be coupled in rotation to a driving shaft, that includes a turbinewheel (40) mounted inside the casing (12) and fixed to a hub (46) whichis arranged to be coupled in rotation to a driven shaft, in which therear face of the transverse front wall (18) of the casing (12) includesa first surface (26), in which a lock-up clutch is interposedoperatively between the turbine wheel (40) and the transverse front wall(18) so as to couple them together releasably, and in which the lock-upclutch comprises at the rear a piston (30) which is movable axially withrespect to the transverse front wall (18) of the casing (12), and whichcarries on its front face a second surface (28) facing the first surface(26), wherein the piston (30) is coupled in rotation to the annularaxial wall (13) of the casing (12) through an axially elastic device(64), wherein the second surface (28) is adjacent the outer periphery ofthe piston (30), and wherein the axially elastic device (64) comprisesat least one support member (66) coupled in rotation and along an axialdirection to the axial annular wall (13) of the casing (12), said atleast one support member (66) comprising a transverse plate element (68,100, 126, 138, 158), and comprises at least one elastic member (74, 136,142, 146, 150) which is interposed axially between the piston (30) andthe transverse plate element (68, 100, 126, 138, 158) of the supportmember (66), and wherein the piston (30) includes means (74, 110, 172)for coupling said piston (30) in rotation with the support member (66).2. Apparatus (10) according to the preceding claim 1, characterised inthat the mean radius of intervention of the elastic member (74, 136,142, 146, 150) is smaller than the external radius of the second surface(28).
 3. Apparatus (10) according to claim 2, characterised in that theaxially elastic device (64) comprises a plurality of support members(66) spaced apart circumferentially, in particular at regular intervals.4. Apparatus (10) according to claim 2, characterised in that theaxially elastic device (64) comprises a single support member (66), thetransverse plate portion (68, 158) of which constitutes an annular ring.5. Apparatus (10) according to claim 1, characterised in that theaxially elastic device (64) comprises axially elastic tongues (74), theopposed ends of which are secured respectively on the piston (30) and onthe transverse plate portion (68, 100, 126) of the support member (66)or members.
 6. Apparatus (10) according to the preceding claim 1,characterised in that the tongues (74) exert a preloading force on thepiston (30) in the direction of locking of the clutch.
 7. Apparatus (10)according to the preceding claim 1, characterised in that the magnitudeof the preloading force is adjusted according to the axial positioningof the transverse plate portion (68, 100, 126).
 8. Apparatus (10)according to claim 5, characterised in that the tongues (74) tend toretain the piston (30) in the unlocked position of the clutch. 9.Apparatus (10) according to claim 5, characterised in that the tongues(74) are spaced apart circumferentially at regular intervals. 10.Apparatus (10) according to claim 5, characterised in that the tongues(74) are oriented tangentially.
 11. Apparatus (10) according to claim 5,characterised in that each tongue (74) includes a first point (76) forfastening on the rear face (78) of the piston (30).
 12. Apparatus (10)according to the preceding claim 1, characterised in that the firstfastening point (76) is defined on a convex boss (84) on the rear face(78) of the piston (30).
 13. Apparatus (10) according to claim 12,characterised in that the tongues (74) are formed integrally with thetransverse plate portion or portions (100) of the or the respectivesupport member (66).
 14. Apparatus (10) according to claim 12,characterised in that each tongue (74) has a second point (80) forfastening on the front face (82) of the transverse plate portion orportions (68, 100, 126) of the or the respective support member (66).15. Apparatus (10) according to the preceding claim 1, characterised inthat the second fastening point (80) of the tongue (74) is in facingrelationship with a concave boss (86) on the rear face (78) of thepiston (30).
 16. Apparatus (10) according to claim 15, characterised inthat the transverse plate portion (68) of the support member (66) isformed with cut-outs (72) in facing relationship with a first fasteningpoint (76) of each tongue (74), the second fastening point (80) of whichis situated in the vicinity of the circumferential terminal edge (73) ofthe cut-out (72).
 17. Apparatus (10) according to claim 1, characterisedin that the piston (30) includes, in facing relationship with its rearface (78), at least one transverse intermediate plate (116) which isfixed through its outer periphery on a peripheral annular skirt (108) ofthe piston (30), whereby the elastic member (74) is operativelyinterposed between each transverse intermediate plate (116) and eachsupport member (66).
 18. Apparatus (10) according to claim 1,characterised in that the casing (12) comprises a front shell (14) and arear shell (16), each of which includes an axial skirt (20, 24), the twoaxial skirts (20, 24) defining the axial annular wall (13) of the casing(12).
 19. Apparatus (10) according to claim 18, characterised in thatthe transverse plate portion (100) of each support member (66) is fixeddirectly on the free rear end of the axial skirt (20) of the front shell(14), or on the free front end of the axial skirt (24) of the rear shell(16).
 20. Apparatus (10) according to claim 18, characterised in thateach support member (66) comprises an annular axial crown (70) orannular axial crown sectors (106, 128, 139), which are oriented towardsthe rear from the outer periphery of the transverse plate portion (68,100, 126, 138), for coupling the support member (66) to the axialannular wall (13) of the casing (12).
 21. Apparatus (10) according toclaim 20, characterised in that the crown (70) or the crown sector (106,128, 139) of each support member (66) is fixed on the axial skirt (20)of the front shell (14) or on the axial skirt (24) of the rear shell(16).
 22. Apparatus (10) according to claim 21, characterised in that adouble-sided annular friction disc (92) is arranged to be grippedbetween the first and second surfaces (26, 28), and in that a torsiondamper (90) is interposed operatively between the annular friction disc(92) and the hub (46) of the turbine (40).